Large etch-selectivity enhancement in the epitaxial liftoff of single-crystal LiNbO3 films

Abstract

We report on a large etch selectivity enhancement in the epitaxial liftoff of He+-implanted single-crystal lithium niobate (LiNbO3) films upon rapid thermal annealing. A buried sacrificial layer is formed by ion implantation. Heat treatment is found to reduce the time needed for film detachment by a factor as large as 100. Implant damage and postanneal stress-induced etch selectivity become nearly independent of implantation energy upon annealing. Large (0.5×1 cm2) 5–10-μm-thick single-crystal LiNbO3 films of excellent quality are detached in just a matter of a few hours.

Integration of Single‐Crystal LiNbO3 Thin Film on Silicon by Laser Irradiation and Ion Implantation– Induced Layer Transfer

“…Similar phenomena have been reported in proton-exchanged LiNbO 3 and high-energy He + implantation of LiNbO 3 . [6,19] However, the transferred LiNbO 3 thin films (Fig. 4, spectra d,e) have the same local mode as the original bulk LiNbO 3 .…”

“…However, considering that much thicker (several micrometer) LiNbO 3 single-crystal films have been reported by Radojevic et al, it should be possible to obtain a moderately thicker film using higher energy (several MeV range) implantation. [6,7] Izuhara et al [7] have also reported freestanding LiNbO 3 layers that are several micrometers thick, suggesting that the transferred LiNbO 3 thickness is ultimately limited by the equipment capability and processing time. Conventional medium-current ; c) after cw-CO 2 laser irradiation of bulk LiNbO 3 ; d) the transferred LiNbO 3 on Si (200 nm); and e) transferred LiNbO 3 on Si (800 nm).…”

“…[4,5] Recently, layer splitting and transfer of ferroelectric materials such as LiNbO 3 , LiTaO 3 , KTaO 3 , SrTiO 3 , and BaTiO 3 have also been demonstrated through a sacrificial wet etching and anodic bonding process combined with a crystal ion slicing method. [6][7][8][9][10][11] However, because of large mismatch in the coefficient of thermal expansion (CTE) between LiNbO 3 ((7.5-14.4) × 10 -6 m°C -1 , depending on cutting orientation) and Si (2.6 × 10 -6 m°C -1 ), thermal mismatch-induced stress at the LiNbO 3 /Si interface occurring during heating and cooling steps in the direct bonding and layer transfer process is quite large in comparison to other material systems. This complicates the development of layer transfer and bonding processes for the integration of LiNbO 3 on silicon.…”

Broadband Electric-Field Sensor Array Technology

“…After implantation, the wafer is annealed using rapid thermal annealing (RTA) and then etched in hydrofluoric acid (HF) solution. 22 Non-uniform stress produces 700 nm thick LiNbO 3 thin films in the areal shape of strips and triangles whose edges are formed along crystal planes. The edge length ranges from several tens of micrometers to several hundred micrometers.…”

Low-voltage nanodomain writing in He-implanted lithium niobate crystals

“…The energy E of the ions was chosen to give 2 an end of range (EOR) compatible with the depth resolution of PFM [12], thus the samples were implanted at 130 and 350 keV, corresponding to EOR of 0.5 and 1 µm, respectively. A more detailed description of the sample preparation can be found elsewhere [13].…”